Method and Device for Producing Zinc

ABSTRACT

A method for producing zinc is disclosed. The method includes an electrolysis step and a reduction step. The electrolysis step includes pressurizing and heating liquid water to a critical state to obtain critical water, and electrolyzing the critical water to obtain super critical state hydrogen and super critical state oxygen. The reduction step includes reacting the super critical state hydrogen with a zinc oxide to reduce the zinc oxide to zinc.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a method and a device for producing zinc from biomass and, more particularly, to a method and a device for producing zinc with improved efficiency while consuming less energy.

2. Description of the Related Art

Zinc can be mixed with nonferrous metals to form an alloy which is widely adapted in electroplating, die casting or mechanical manufacturing. In another application, the alloy can also be used to make electrodes for solar batteries, such as zinc-copper batteries or zinc air batteries. However, zinc easily reacts with oxygen in the air as an undesired effect. For example, the zinc air battery with zinc electrodes tends to have a precipitate of zinc oxide after the battery is completely discharged. Although the zinc oxide spreading all over the zinc can serve a protection therefore, it still causes an inconvenience in use at the same time.

Conventionally, zinc oxide is reduced to zinc through use of solid carbon. However, the reaction between the solid carbon and the zinc oxide only occurs at a temperature of 1200K. Therefore, it requires much more heat when the solid carbon is used as a reductant performing the reduction reaction of the zinc oxide, thereby consuming more energy. Further, the solid carbon as a solid reductant has a less even mixture with the zinc oxide compared to liquid or gaseous reductant, leading to an incomplete utilization of the solid carbon. As a result, a longer period of reaction time and higher costs are resulted, failing to meet the economical needs.

As the continuous development of biomass technology, the conversion and utilization of biomass have been commonly seen in various chemical processes. As an example, hydrogen molecules and oxygen molecules contained in waste water can be recycled for future use. It is hoped that the reaction between the hydrogen molecules and the zinc oxide layer (the solid zinc oxide) can reduce the zinc oxide layer to zinc with lesser energy consumption while attaining recycling of environmental waste water.

Conventionally, water is electrolyzed at a normal pressure and a normal temperature. However, the bond strength between the hydrogen molecules and the oxygen molecules of liquid water at the normal temperature and normal pressure does not permit separation of the hydrogen molecules from the oxygen molecules. Therefore, an external strong current must be provided to electrolyze the liquid water to obtain gaseous hydrogen molecules and gaseous oxygen molecules, which consumes considerable energy and takes a long period of time of electrolysis to release sufficient gaseous hydrogen molecules. Thus, the yield of the gaseous hydrogen molecules is low, because it is obviously limited to the reaction time of water electrolysis. The production efficiency and yield of subsequently formed zinc are also adversely affected.

Furthermore, during the process of electrolyzing the liquid water into gaseous hydrogen and gaseous oxygen, only the gaseous hydrogen molecules are used to react with the zinc oxide to obtain zinc while leaving the gaseous oxygen molecules unused, leading to a waste and failing to meet the goal of recovering energy.

Thus, a need exists for a method and a device for improving production rate of zinc in spirit of energy recycling.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a method for producing zinc by using gaseous hydrogen obtained from electrolyzing critical state liquid water that consumes less energy, effectively increasing the electrolyzing efficiency of the liquid water.

Another objective of the present invention is to provide a method for producing zinc for increasing the yield of gaseous hydrogen, effectively increasing the production efficiency of zinc.

A further objective of the present invention is to provide a device for producing zinc that consumes less energy, thereby effectively saving energy.

Still another objective of the present invention is to provide a device for producing zinc that can recycle and store gaseous oxygen obtained from electrolyzing critical state liquid water to reuse energy.

The present invention fulfills the above objectives by providing, in an aspect, a method for producing zinc. The method includes an electrolysis step and a reduction step. The electrolysis step includes pressurizing and heating liquid water to a critical state to obtain critical water, and electrolyzing the critical water to obtain super critical state hydrogen and super critical state oxygen. The reduction step includes reacting the super critical state hydrogen with a zinc oxide to reduce the zinc oxide to zinc.

Preferably, the liquid water in the critical state has a pressure of 221 atm and a temperature of 672K. Preferably, the super critical state hydrogen and the super critical state oxygen have a pressure of 230 atm and a temperature of 700K.

Preferably, the method for producing zinc further comprises a pre-step including heating and pressurizing the liquid water into a high temperature/high pressure state, with the liquid water in the high temperature/high pressure state having a pressure of 20 atm and a temperature higher than 330K.

In another aspect, a device for producing zinc including at least one adjustment unit, an electrolysis unit and a reduction unit is disclosed. Each adjustment unit has a pressurizing member and a heating member. The electrolysis unit is connected to the adjustment unit by a pipe and outputs a critical state gas. The reduction unit is connected to the electrolysis unit by a gas inlet pipe.

Preferably, the device for producing zinc further comprises a reservoir, with the at least one adjustment unit having two adjustment units connected between the reservoir and the electrolysis unit.

Preferably, the device for producing zinc further comprises a storage tank connected to the electrolysis unit by a gas outlet pipe.

Preferably, the device for producing zinc further comprises a plurality of heat dissipating members mounted between the electrolysis unit and the storage tank.

Preferably, the electrolysis unit is connected to a current supplier supplying the electrolysis unit with electric current.

The present invention will become clearer in light of the following detailed description of illustrative embodiments of this invention described in connection with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The illustrative embodiments may best be described by reference to the accompanying drawings where:

FIG. 1 shows a flowchart illustrating a method for producing zinc according to the present invention.

FIG. 2 shows a schematic diagram of a device for producing zinc of an embodiment according to the present invention.

FIG. 3 shows a schematic diagram of a device for producing zinc of another embodiment according to the present invention.

All figures are drawn for ease of explanation of the basic teachings of the present invention only; the extensions of the figures with respect to number, position, relationship, and dimensions of the parts to form the preferred embodiments will be explained or will be within the skill of the art after the following teachings of the present invention have been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following teachings of the present invention have been read and understood.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, a method for producing zinc according to the present invention includes a pre-step S1, an electrolysis step S2 and a reduction step S3.

In the pre-step S1, liquid water is turned into a high temperature/high pressure state. Specifically, the liquid water is pressurized at a normal temperature. This turns the liquid water into a high pressure state when the pressure of the liquid water is higher than 1 atm. Next, the liquid water in the high pressure state is heated such that the liquid water turns into a high pressure/high temperature state, as shown in a chemical equation 1 below.

H₂O_((λ, T1, P1))→H₂O_((λ, T2, P2))   (1)

wherein T1=298K, P1=1 atm, T2=400K, and P2=20 atm.

The term “normal temperature” referred to herein means 298K, which can be appreciated by one skilled in the art. The term “high temperature” referred to herein means a temperature higher than the normal temperature. The term “normal pressure” referred to herein means 1 atm, which can be appreciated by one skilled in the art. The term “high pressure” referred to herein means a pressure higher than the normal pressure.

As an example, in this embodiment, a pump is provided to compress the liquid water at 1 atm and 298K to 20 atm and 330K. Then, the liquid water at 20 atm and 330K is gradually heated to 400K.

In the electrolysis step S2, the liquid water in the high pressure/high temperature state is pressurized and heated to a critical state to obtain critical water. The critical water can be electrolyzed to obtain super critical state hydrogen and super critical state oxygen.

Specifically, in the electrolysis step S2, the liquid water in the high pressure/high temperature state is first pressurized and then heated to the critical state to obtain the critical water. At this time, the bond strength of the hydrogen bond of the critical water molecule is significantly lower than that of the water molecule at the normal temperature/normal pressure. Thus, the bond-dissociation energy of the critical water molecule can be rapidly reached even under low-current electrolysis, thereby rapidly obtaining the super critical state hydrogen and the super critical state oxygen (see a chemical equation 2 below).

2H₂O_((λ, T2, P2))→2H₂O_((λ, T3, P3))

2H₂O_((λ, T3, P3))→2H_(2(g, T4, P4))+O_(2(g, T4, P4))   (2)

wherein T3=672K, P3=221 atm, T4=700K, and P4=230 atm.

As an example, in this embodiment, the liquid water at 20 atm and 400K is compressed to 221 atm and then gradually heated to 672K, thereby turning the liquid water at 20 atm and 400K into the critical water. Then, an electrical current is supplied to perform electrolysis. After reaching the bond-dissociation energy of the critical water, gaseous hydrogen and gaseous oxygen can be separated from the critical water. The gaseous hydrogen and the gaseous oxygen are maintained in the super critical state at 230 atm and 700K. The super critical state hydrogen serves as another material for subsequent synthesis of zinc while the super critical state oxygen is recycled and stored for use in industrial processes.

In the reduction step S3, the super critical state hydrogen reacts with a solid zinc oxide to reduce the zinc oxide to zinc. Specifically, in the embodiment, the super critical state hydrogen at 230 atm and 700K is provided to react with the solid zinc oxide to obtain zinc, as shown in a chemical equation 3 below.

H_(2(g, T4, P4))+ZnO_((s, T1))→ZnO_((s, T5))+H₂O_((g, T5, P5))   (3)

wherein T5=730K, and P5=77 atm.

The liquid water can easily be pressurized and heated because liquid molecules have a tighter molecular alignment than gaseous molecules. Furthermore, the liquid water rapidly turns into the critical water under second-time heating and pressurization to reduce the bond strength between the hydrogen molecules and the oxygen molecules. Thus, the bond-dissociation energy of the hydrogen molecules and the oxygen molecules can easily be reached by electrolysis, rapidly separating the super critical state hydrogen and the super critical state oxygen from the critical water. In this way, the production efficiency of the gaseous hydrogen is increased, and the gaseous hydrogen can react with the solid zinc oxide to obtain zinc. Therefore, the proposed method for producing zinc increases the production efficiency of the gaseous hydrogen from electrolyzing the liquid water by using the critical state while increasing the yield of the gaseous hydrogen in a short period of time. Through reaction of a large amount of gaseous hydrogen and the solid zinc oxide, the production efficiency and yield of zinc can be increased.

Since the liquid water can turn into the critical state rapidly, the invention is able to obtain the super critical state hydrogen and the super critical state oxygen from electrolyzing the critical water while consuming less energy. Therefore, the pre-step Si can be omitted while only the electrolysis step S2 is adapted to directly heat and pressurize the liquid water to the critical state, as would be obvious to one skilled in the art.

FIG. 2 shows a device for producing zinc according to a preferred embodiment of the invention, in which the zinc-producing device serves the purpose of illustrating the zinc-producing method discussed above.

The zinc-producing device includes an adjustment unit I, an electrolysis unit 2 and a reduction unit 3. The units 1, 2 and 3 are connected by different pipes to form a continuous passage of the zinc-producing device, which is described in detail as follows.

The adjustment unit 1 includes a pressurizing member P and a heating member H. The pressurizing member P is preferably a pump that can increase the pressure of liquid water. The heating member H is provided to increase the temperature of the liquid water.

The electrolysis unit 2 is connected to the adjustment unit 1 by a pipe T1 for outputting critical state gas. Therefore, the liquid water flowing in the pipe T1 can rapidly reach the critical state by using the pressurizing member P and the heating member H, obtaining the critical state water rapidly. Based on this, the electrolysis unit 2 can electrolyze the critical water to rapidly obtain the super critical state hydrogen and the super critical state oxygen. In the embodiment, the electrolysis unit 2 includes a current supplier 21 that supplies an electrical current to perform electrolysis. After reaching the bond-dissociation energy of the critical water, the electrolysis unit 2 can electrolyze the critical water to obtain the super critical state hydrogen and the super critical state oxygen.

The reduction unit 3 is connected to the electrolysis unit 2 by a gas inlet pipe T21 that allows the super critical state hydrogen to be sent from the electrolysis unit 2 to the reduction unit 3. In this embodiment, the reduction unit 3 contains solid zinc oxide so that the reduction reaction between the super critical state hydrogen and the solid zinc oxide can be performed. In this way, the solid zinc oxide can be reduced to zinc for use in industrial processes.

Furthermore, the electrolysis unit 2 may also be connected to a storage tank 4 by a gas outlet pipe T22. The gas outlet pipe T22 can allow the super critical state oxygen to be sent from the electrolysis unit 2 to the storage tank 4 for storage. The stored super critical state oxygen can be used in other industrial processes. In addition, a plurality of heat dissipating members (not shown) may be mounted between the electrolysis unit 2 and the storage tank 4 for cooling purpose.

Referring to FIG. 3, the device for producing zinc of the invention may further includes a reservoir 5 that recycles waste water. The reservoir 5 stores the liquid water and allows the liquid water to flow into subsequent pipes. The reservoir 5 is preferably in the form of a cooling water tower to cool down and recycle the liquid water that contains a lot of waste heat. Thus, lesser energy is consumed for substantial pressurization and heating operations.

Moreover, two adjustment members 1 and 1′ may be further arranged between the electrolysis unit 2 and the reservoir 5. The adjustment member 1 includes a pressurizing member P and a heating member H, and the adjustment member 1′ includes a pressurizing member P′ and a heating member H′. The heating member H is connected between the two pressurizing members P and P′ via the pipe T1. The heating member H′ is connected between the pressurizing member P′ and the electrolysis unit 2. The pressurizing member P compresses the liquid water flowing in the pipe T1 from the reservoir 5 so as to increase the pressure of the liquid water. At the same time, the heating member H heats the high pressure liquid water so that the liquid water turns into a high temperature/high pressure state. Then, the pressurizing member P′ further compresses the high temperature/high pressure liquid water to a critical pressure value. Then, the liquid water at the critical pressure value is heated by the heating member H′ to a critical temperature value to obtain the critical water, which is subsequently provided to the electrolysis unit 2. Based on this, the current supplier 21 may supply an electrical current to perform electrolysis. After reaching the bond-dissociation energy of the critical water, the electrolysis unit 2 can electrolyze the critical water to obtain the super critical state hydrogen and the super critical state oxygen. At this time, the reduction unit 3 may perform the reduction reaction. The detailed structure and operational principle of the electrolysis unit 2 are known to one skilled in the art, so they are not described in detail to avoid redundancy.

The proposed method for producing zinc can be operated on the zinc-producing device with simple connection equipment to increase the production efficiency of gaseous hydrogen by electrolysis of liquid water. Furthermore, through reaction of a large amount of gaseous hydrogen with the solid zinc oxide, the production efficiency and yield of zinc can be increased. Further, the proposed zinc-producing device can reduce the energy loss during the process. Still further, the gaseous oxygen not used in the reaction can be recycled and stored, further saving and reusing energy.

In the proposed zinc-producing method, the electrolyzing efficiency of the liquid water can easily be enhanced by using gaseous hydrogen obtained from electrolyzing critical state liquid water that consumes less energy.

In the proposed zinc-producing method, the yield of gaseous hydrogen can be increased to effectively increase the production efficiency of zinc.

In the proposed zinc-producing device, the energy consumed for producing zinc is reduced to effectively save energy.

In the proposed zinc-producing device, gaseous oxygen obtained from electrolyzing critical state liquid water can be recycled and stored to reuse energy.

Thus since the invention disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope of the invention is to be indicated by the appended claims, rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein. 

1. A method for producing zinc comprising: an electrolysis step including: pressurizing and heating liquid water to a critical state to obtain critical water, and electrolyzing the critical water to obtain super critical state hydrogen and super critical state oxygen; and a reduction step including reacting the super critical state hydrogen with a zinc oxide to reduce the zinc oxide to zinc.
 2. The method for producing zinc as claimed in claim 1, with the liquid water in the critical state having a pressure of 221 atm and a temperature of 672K.
 3. The method for producing zinc as claimed in claim 1, with the super critical state hydrogen and the super critical state oxygen having a pressure of 230 atm and a temperature of 700K.
 4. The method for producing zinc as claimed in claim 1, further comprising a pre-step including heating and pressurizing the liquid water into a high temperature/high pressure state, with the liquid water in the high temperature/high pressure state having a pressure of 20 atm and a temperature higher than 330K.
 5. A device for producing zinc comprising: at least one adjustment unit each having a pressurizing member and a heating member; an electrolysis unit connected to the adjustment unit by a pipe and outputting a critical state gas; and a reduction unit connected to the electrolysis unit by a gas inlet pipe.
 6. The device for producing zinc as claimed in claim 5, further comprising a reservoir, with the at least one adjustment unit having two adjustment units connected between the reservoir and the electrolysis unit.
 7. The device for producing zinc as claimed in claim 5, further comprising a storage tank connected to the electrolysis unit by a gas outlet pipe.
 8. The device for producing zinc as claimed in claim 7, with a plurality of heat dissipating members mounted between the electrolysis unit and the storage tank.
 9. The device for producing zinc as claimed in claim 5, with the electrolysis unit connected to a current supplier supplying the electrolysis unit with electric current. 